Method of and apparatus for electroforming metal articles



R. M. FIANDT METHOD OF AND APPARATUS FOR ELECTROFORMING METAL ARTICLES April 1 7, 1951 2 Sheets-Sheet 1 Filed Aug. 25, 1946 IIL inHHUWbw Apnl 17, 1951 R. M. FIANDT 2,549,678 METHOD OF AND APPARATUS FOR ELECTROFORMING METAL ARTICLES Filed Aug. 23, 1946 v2 Sheets-Sheet 2 steel.

Patented Apr. 17, 1951 METHOD OF AND APPARATUS FOR ELEC- TROFORMING METAL ARTICLES Ronald M. Fiandt, Elkhart, Ind, assignor to C. G.

Conn, Ltd, Elkhart, Ind., a corporation of Indiana Application August 23, 1946, Serial No. 692,606

'7 Claims. (Cl. 204- 9) This-invention relates to method of and apparatus for electroforming metal articles and more specifically to the electroforming of copper horn bells.

One of the objects of the invention is to provide a method of and apparatus for electroforming metal articles quickly and efliciently with a minimum of surface finishing required after forming.

Another object is to provide a method of and apparatus for electroforming metal articles in which the electrolyte is enriched outside of the depositing tank and is constantly circulated through the depositing tank.

Still another object is to provide a method of and apparatus for electroforming metal articles in which the circulating electrolyte causes the cathode to turn in the solution.

Still another object is to provide a method of I and apparatus for electroforming copper articles in which the copper content of the electrolyte is replenished by alternately submerging copper particles in the electrolyte and then exposing them to air.

' A further object is to provide a cathode for electroforming which is made of smooth stainless cient since metal will deposit on but not adhere readily to it and since it produces a desirable surface finish on the formed article.

The above and other objects and advantages of the invention will be apparentfrom the following description when read in connection with the accompanying drawings, in which Figure l is a diagrammatic plan view of apparatus embodying the invention;

Figure 2 is a diagrammatic side elevation; and

Figure 3 is a transverse section through a depositing tank on theline 3-3 of Figure 1.

The invention is illustrated and will be described in connection with the electrofor-ming of copper horn bells, although it will be apparent as the description proceeds that various of the features are applicable to the formation of other articles and to the depositing of metals other than copper.

In forming copperhorn bells according to the invention, copper particles such as trimmings and like copper scrap, are placed in'a corrosion tank It! which may conveniently be located in a pit ll as shown. The bottom of the tank it) is connected through a valved pipe to the inlet of a pump 52 whose outlet pipe i3 discharges into a receiving tank It above the pit The tank It is connected at its bottom to two valved discharge- A cathode of this character is highly efiipipes and I6 discharging respectively into the tank IE3 and a storage tank ll. The tank I! is connected, as shown, to the inletof the pump l2.

The apparatus as so far described is used to corrode the copper to form a copper sulphate solution from which copper can be deposited. For this purpose a sulfuric acid solution is poured over the copper particles in the tank Ill. After remaining in this tank for a short time, the solu tion is pumped by pump l2 into the receiving tank [4, allowing air to enter to open top of the tank Ii] to contact the copper particles. This causes a film of copper oxide to form on the particle surfaces which can be dissolved, forming copper sulfate, by returning the solution to the tank In from the tank [4' through the pipe I5. By repeating this process a copper sulphate solution of the desired strength can be built up quickly and efficiently with a minimum of apparatus. The solution so formed may be stored in tank i l or storage tank I! until it isto be used.

The actualelectroforming isaccomplished, according to the invention, in one or more'separate depositing tanks 18. The enriched solution is pumped from the tank M by a pump is upwardly through a filter Z! and through a pipe 22 into the depositing tanks. If desired the solution may be circulated through the filter several times by returning it from the filter to the tank it through avalved return pipe 23. In this way the depositing tanks are supplied with a clear enriched solution free from suspended solids which might cause irregularities in the deposit.

The depositing tanks 18 as best seen in Figure 3 may be lined with a material inert to the electrolyte and may contain coils, for either heating or cooling, to keep the solution at the desired temperature. Each tank l8 may contain a series of anodes and cathodes for simultaneously electroforming a plurality of'articles; the cathodes as shown at 25 being elongated and taperedv to conform to'the shape of a horn bell.

According to one of the features of the invention, the cathodes. 25 are made of stainless steel and have their surfaces smooth and polished. I have found that copper will readily deposit on a cathode of this type but can easily be stripped from it and will have a smooth regular surface.

Each cathode 25"has mounted around it an annular anode 26 of inert material such as lead. In the preferred arrangement shown in Figure 3 the cathodes are mounted vertically'with their large ends at the top. The anodes flare downward with theirminimum diameter tops fitting closely around the bell portions of the anodes.

'3 This arrangement insures proper and even deposition of metal on the cathode.

During the depositing operation the solution is constantly circulated through the depositing tanks. For this purpose an outlet pipe 2'! extends longitudinally through the lower part of each tank and is perforated throughout its length as shown at 28. The pipe 27 connects to the inlet of a pump 29 which discharges into a manifold 3i lying beside the tank. Adjacent each cathode the manifold connects to a discharge pipe 32 extending into the tank and terminating in an upwardly turned end directly below the cathode. With the pump 29 running, solution will constantly be withdrawn through the pipe 21 and returned through the pipes 32 to flow upward around the cathodes and through the annular spaces between the cathodes and anodes, This enables the copper to be deposited rapidly and uniformly.

Uniformity of deposit is further increased by rotating the cathodes. To this end each cathode is supported by a vertical shaft 33 journaled in a bearing 34 at the top of the tank. Each shaft 33 carries an annular set of vanes 35 adjacent the top of the cathode to receive solution discharging between the cathode and the anode. The vanes 35 may be set at the required angle to cause the cathode to rotate at a desired rate in response to circulation of the solution.

When a horn bell is formed to the desired thickness on a cathode, the cathode may be removed from the tank and the bell stripped therefrom. The cathode may then be returned to the tank for another forming operation. When the solution in a tank becomes depleted it may be returned to the tank H] through a valved return pipe 3% connected to the pipe 21 and freshly enriched solution may be pumped into the depositing tank from the tank M. It will be seen that one corroding apparatus may serve several depositing tanks and that the depositing tanks may be kept in substantially continuous operation except for the time required to drain depleted solution therefrom and pump fresh solution thereto.

While the invention has been described in connection with one specific application, it 'will be apparent that many of its features are applicable to the formation of different articles from different metals. It is therefore not intended to limit the scope of the invention to the exact application shown and described nor otherwise than by the terms of the appended claims.

What is claimed is:

1. Apparatus for electroforming horn bells or the like comprising a depositin tank to contain an electrolyte having a solution of the metal to be deposited, an elongated cathode of a material to which metal does not readily adhere extending vertically into the central part of the tank and tapering from its upper end to a minimum diameter at its bottom, an annular anode of inert material around and spaced from the cathode and flaring from a minimum diameter at its upper end to a maximum diameter at its lower end, a solution inlet pipe discharging upwardly adjacent the lower end of the cathode, means for maintaining a constant circulation of solution from the inlet pipe for passage between the cathode and anode for the entrance end defined by the largest spaced relation between the cathode and anode to the outlet end defined by the least spaced relation therebetween, means supporting the cathode for rotation about a vertical axis,

4 and angularly disposed vanes attached to the supporting means just beyond the outlet end within the tank to rotate the cathode in response to reaction with the circulating electrolyte.

2. In a method for electroforming copper articles, the steps of successively exposing copper metal particles to oxidizing conditions for forming the respective oxides of copper and then dissolving the oxides in spent electrolyte solution to replenish the ion copper concentration therein, and then conductin the replenished electrolyte to an electrolytic cell containing an anode and a cathode submerged therein under operating conditions, said cathode being formed of a material to which electrodeposited copper is non adherent, passing electrical current from the anode through theelectrolyte to the cathode to deposit copper on the cathode, and stripping the deposit when formed to the desired shape from the cathode.

3. Apparatus for electroforming coppe horn bells for musical instruments comprising an electrolytic cell to receive electrolyte containing cop'- per in solution, .a cathode conforming to the contour of the horn bell extending vertically into the central part of the cell with the flared-out bell portion uppermost and with minimum diameter in the lowermost region, an anode of inert material concentrically spaced about the cathode and tapering from a minimum diameter at the top to a maximum diameter at the base, means for circulating electrolyte between the anode and cathode whereby maximum flow occurs in the region of the flared-out end portion of the cathode.

4. Apparatus for electroforming copper horn bells for musical instruments comprising an electrolytic cell to receive electrolyte containing copper in solution, a cathode conformin to the shape of the horn to be formed and a conicall shaped anode of inert material arranged concentrically in spaced relation with the cathode but with the taper of the anode being inverse to the taper of the cathode whereby the maximum spaced relation exists in the region of smallest diameter of the horn and the least spaced relation is in the region of the flared-out bell portion of the horn, and means for directing the circulation of the electrolyte substantially in an axial direction between the anode and cathode whereby most rapid flow occurs in the region having the least spaced relation between the cathode and anode.

5. Apparatus for electroforming copper horn bells for musical instruments comprising an electrolytic cell to receive electrolyte containing copper in solution, a cathode conforming to the shape of the horn to be formed and a conically shaped anode of inert material arranged concentrically in spaced relation with the cathode but with the taper of the anode being inverse to the taper of the cathode whereby the maximum spaced relation exists in the region of smallest diameter of the horn and the least spaced relation is in the region of the flared-out bell portion of the horn, means for directing the circulation between the anode and cathode whereby rapid flow occurs in the region of the flared-out bell portion of the cathode, means supporting the cathode for rotation about a vertical axis, and varies within the cell attached to the supporting means adjacent the region of the flared-out end portion of the horn said vanes being angularly disposed to rotate the cathode in response to fluid flow of the electrolyte as it emerges from the region between the anode and cathode.

6. In a method for electroforming copper horn bells for musical instruments, the steps of continuously circulating an acidulou electrolyte containing copper ion in solution through an electrolytic cell having a cathode that conforms to the contour of the horn bell and an anode arranged concentrically about the cathode in spaced relation with the taper of the anode being in the opposite direction than the taper of the cathode, causing the electrolyte topass in a con tinuous fiowbetween the cathode and anode in one direction from an inlet end having the greatest spaced relation to the outlet end having the least spaced relation between the cathode and anode, whereby maximum fluid flow of the electrolyte occurs in the region of the flared out bell portion and passing electrical current fromthe anode through the electrolyte to the cathode to effect copper deposition.

7. In a method for electroforming copper horn bells for musical instruments, the steps of continuously circulating an acidulous electrolyte containing copper ion in solution through an electrolytic cell having a cathode that conforms to the contour of the horn bell and an anode arranged concentrically about the cathode in spaced relation with the taper of the anode being in the opposite direction than the taper of the cathode, causing the electrolyte to pass in a continuous flow between the cathode and anode in one direction from an inlet end having the greatest spaced relation to the outlet end having the least spaced relation between the cathode and anode, whereby maximum fluid flow of the electrolyte occurs in the region of the flared out bell portion, constantly rotating the cathode REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 519,595 Thofehrn May 8, 1894 680,408 Cowper-Coles Aug. 13, 1901 788,862 Walker May 2, 1905 895,163 Cowper-Cole's Aug. 4, 1908 903,164 Borgnet Nov. 10, 1908 1,280,249 Landry Oct. 1, 1918 1,601,690 Merritt Sept. 28, 1926 1,862,745 Fuller et al June 14, 1932 1,941,376 Wilkins Dec. 26, 1933 2,011,638 Jephson Aug. 20, 1935 2,129,479 Ross Sept. 6, 1938 2,188,472 Campbell Jan. 30, 1940 FOREIGN PATENTS Number Country Date 23,679 Great Britain -4 of 1894 429,206 Great Britain of 1935 805,918 France of 1936 OTHER REFERENCES The Metal Industry (volume 25) January 1927, pages 7-9.

Proceedings of Educational Sessions of American Electroplaters Society, 32nd Annual Convention, June 12, 13, 14, 1944, pages 183, 184. 

1. APPARATUS FOR ELECTROFORMING HORN BELLS OR THE LIKE COMPRISING A DEPOSITING TANK TO CONTAIN AN ELECTROLYTE HAVING A SOLUTION OF THE METAL TO BE DEPOSITED, AN ELONGATED CATHODE OF A MATERIAL TO WHICH METAL DOES NOT READILY ADHERE EXTENDING VERTICALLY INTO THE CENTRAL PART OF THE TANK AND TAPERING FROM ITS UPPER END TO A MINIMUM DIAMETER AT ITS BOTTOM, AN ANNULAR ANODE OF INERT MATERIAL AROUND AND SPACED FROM THE CATHODE AND FLARING FROM A MINIMUM DIAMETER AT ITS UPPER END TO A MAXIMUM DIAMETER AT ITS LOWER END, A SOLUTION INLET PIPE DISCHARGING UPWARDLY ADJACENT THE LOWER END OF THE CATHODE, MEANS FOR MAINTAINING A CONSTANT CIRCULATION OF SOLUTION 